We are endeavoring to discover the function and biological role of secondary natural products (especially alkaloids) in plants and fungi. Our work involves a study of the biosynthesis of these compounds, and also their metabolism in the healthy plants where they are produced. The compounds to be examined include: nicotine, nornicotine, anatabine (in Nicotiana species); mimosine (in Mimosa pudica); lupanine (in Lupinus hartwegii); annotinine, lycopodine (in Lycopodium annotinum) cocaine, hyoscyamine (in Erythroxylon coca, Datura species); retronecine (in Crotalaria species); cephalotaxine (in Cephalotaxus species); vincaleukoblastine (in Catharanthus roseus); tetrahydrocannabinol (in Cannabis sativa). The use of precursors labeled with contiguous 13C-atoms will be exploited, since such atoms are readily detected in the 13C-NMR spectra of these compounds and in the ultimate natural products. The capacity of plants to carry out aberrant biosyntheses will be examined. The stereochemistry of the enzyme controlled reactions will be studied.